Back in February, I was in a park near Manchester airport. I had been walking through a huge field of grass, and I was only 5 metres away from the asphalt alley, when suddenly I wondered: "Hang on a second, does the grass underneath me actually feel pain when I'm walking on it?".

So I stopped (just in case I didn't hurt any more grass). My mind told me it didn't feel pain. But my heart, my feelings, felt as if the grass did feel pain.

I stood there for many minutes, wondering what to do. I only had 5 or so metres to cross, and then I'd be on the asphalt. But I just didn't want to hurt the grass!

So, perhaps out of a sense of humour, I asked myself: "Well, can I fly?". "Yes, through psychic powers."...

Anyway, since it was obvious I couldn't fly, and I couldn't stay there forever, with great care, as if I was a burglar in someone's home, I tread as lightly as I possibly could on the remaining 5 metres of grass, and in doing so, in my mind apologizing to the grass...

Well, I hope that made you laugh! Seriously, though, now I think that plants don't feel pain. The Buddha, as far as I am aware, never said they feel pain. After all, modern science would say you need a nervous system to be able to feel pain, and plants lack such a system.

But it does make you wonder. They are life forms. They have great sensitivity. They arise from a seed, then they grow and mature, then they wither away (grow old), and then they die. They are so different from animals, yet they have certain similarities - some can even "eat" insects!

Plants are awesome! I adore them, as I adore nature. I wish I knew for real the answer to my original question in the park: "Do they actually feel pain?", because then... maybe I should not only not walk on grass (as I strove to avoid walking on it in the weeks and months after that experience, just in case), but maybe not even eat them. But then, since I'm already a vegetarian (vegan from January 1), I'd have nothing to eat...

In the 1st noble truth, suffering seems to have been summarized as attachment (upadana) to the five aggregates. The plants mental construct upadana?

Only a jainist will feel that plants have feelings. Jainism advocated its followers to avoid eating even seeds of plants as it was believed it has feelings.
Lord Buddha in his explanation of Paticca Samuppada has clearly indicated that it is vingnana which fabricates perceptions involving citta with kusala mula and akusala mula leading to karma and its results. Therefore as plants are only formed of form or rupa (apo tejo vayo patavi) without nama (mind) we do not have to consider that plant life has clinging or upadana. As there is no upadana plants do not undergo vedana or suffering.

Only a jainist will feel that plants have feelings. Jainism advocated its followers to avoid eating even seeds of plants as it was believed it has feelings.
Lord Buddha in his explanation of Paticca Samuppada has clearly indicated that it is vingnana which fabricates perceptions involving citta with kusala mula and akusala mula leading to karma and its results. Therefore as plants are only formed of form or rupa (apo tejo vayo patavi) without nama (mind) we do not have to consider that plant life has clinging or upadana. As there is no upadana plants do not undergo vedana or suffering.

In Buddhism, there is a Vinaya rule against eating seeds too. I forget which Vinaya passage. It's not clear if that rule applies to lay people or not.

And then there is also a rule that monastics cannot harm plant life (Pac.10, 11).

Only a jainist will feel that plants have feelings. Jainism advocated its followers to avoid eating even seeds of plants as it was believed it has feelings.
Lord Buddha in his explanation of Paticca Samuppada has clearly indicated that it is vingnana which fabricates perceptions involving citta with kusala mula and akusala mula leading to karma and its results. Therefore as plants are only formed of form or rupa (apo tejo vayo patavi) without nama (mind) we do not have to consider that plant life has clinging or upadana. As there is no upadana plants do not undergo vedana or suffering.

In Buddhism, there is a Vinaya rule against eating seeds too. I forget which Vinaya passage. It's not clear if that rule applies to lay people or not.

And then there is also a rule that monastics cannot harm plant life (Pac.10, 11).

Even if plants do feel pain, I imagine it is a very low level type of pain, more of a biological reaction (in a similar way to the way they move toward sunlight), certainly not comparable to an animal's pain when getting injured or killed. We have to draw the line somewhere in terms of which lives are worthy of protection from killing.

1. Humans
2. + All other mammals
3. + All medium to large animals, including those in the seas
4. + All small animals about the size of a worm or larger
5. + All animals including insects
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6. + Plants
7. + Bacteria, algae, microorganisms not visible to the naked eye

In my opinion, a clear demarcation line exists at number 5 and above. Animals have advanced nervous systems, sentience and consciousness and clearly feel pain and suffering. Drawing the line below numbers 6 or 7 would be too extreme and not realistic and probably not even possible.

Only a jainist will feel that plants have feelings. Jainism advocated its followers to avoid eating even seeds of plants as it was believed it has feelings.
Lord Buddha in his explanation of Paticca Samuppada has clearly indicated that it is vingnana which fabricates perceptions involving citta with kusala mula and akusala mula leading to karma and its results. Therefore as plants are only formed of form or rupa (apo tejo vayo patavi) without nama (mind) we do not have to consider that plant life has clinging or upadana. As there is no upadana plants do not undergo vedana or suffering.

In Buddhism, there is a Vinaya rule against eating seeds too. I forget which Vinaya passage. It's not clear if that rule applies to lay people or not.

And then there is also a rule that monastics cannot harm plant life (Pac.10, 11).

The question now is why were these rules instituted by the Buddha?

Lord buddha was advanced by many jainists as it was a contemporary religion based mainly on extreme Ahimsa. Wheras buddhism was based on the four noble truths the jainist ascetics are said to have turned buddha sravaka.
Samannapala sutta is one sutta where the lines of differences in jainism and buddhism id seen. A research text " Jainism in Buddhist literature" written by Dr. Hiralal Jain in Vidyodaya university Colombo under the guidance of Dr. Ven Balangoda Ananda Maitri is a book which shows the differences and parallels of the two religions jainism and Buddhism in detail.

Samannapala sutta is one sutta where the lines of differences in jainism and buddhism id seen. A research text " Jainism in Buddhist literature" written by Dr. Hiralal Jain in Vidyodaya university Colombo under the guidance of Dr. Ven Balangoda Ananda Maitri is a book which shows the differences and parallels of the two religions jainism and Buddhism in detail.

The author was actually Dr. Bhagchandra Jain Bhaskar. Dr. Hiralal only wrote the foreword. It's available here:

Samannapala sutta is one sutta where the lines of differences in jainism and buddhism id seen. A research text " Jainism in Buddhist literature" written by Dr. Hiralal Jain in Vidyodaya university Colombo under the guidance of Dr. Ven Balangoda Ananda Maitri is a book which shows the differences and parallels of the two religions jainism and Buddhism in detail.

The author was actually Dr. Bhagchandra Jain Bhaskar. Dr. Hiralal only wrote the foreword. It's available here:

There seem to be two prevailing reasons: 1) Because other beings may inhabit plants (in the way a spirit may possess something), and so to intentionally destroy plants would entail harm to those beings as well, and 2) To protect the sangha from condemnation by others who hold the belief that plants, having the sense of touch, are a form of life to be cherished. Thus, damaging plant life is a pacittiya, a rule entailing confession.

On this occasion the Buddha, the Blessed One, was dwelling at Āḷavi, at the Aggāḷava Cetiya. Furthermore, on this occasion, Āḷavi monks were performing new work, cutting trees and causing them to be cut. A certain Āḷavi monk cut a tree. The deva living in that tree said to that monk, “Bhante, don't cut my dwelling-place out of a desire to make a dwelling-place for yourself.” The monk, not taking heed, cut anyway, and that deva's son's arm was struck. Then that deva thought, “What if I were to deprive this monk of life right here?” Then that deva thought, “That would not be proper for me, if I were to deprive this monk of life right here. What if I were to report this matter to the Blessed One?” Then that deva approached the Blessed One; after approaching, she reported this matter to the Blessed One. “Excellent, excellent, deva! It is very good that you, deva, did not deprive that monk of life. Deva, if you had deprived that monk of life today, you would have accumulated much demerit. Go, deva, in that open space there is a solitary tree; you may take that [tree].”

People denounced, criticized, and castigated: “How is it that Sakyan-son contemplatives will cut trees and cause them to be cut? Sakyan-son contemplatives are damaging single-faculty life!” Other monks heard of the people denouncing, criticizing, and castigating. Those monks who were of few wishes, [content, modest, conscientious, desirous of training], denounced, criticized, and castigated: “How is it that Āḷavi monks will cut trees and cause them to be cut?” ... Then those monks... reported this matter to the Blessed One.

[The Buddha, the Blessed One, reprimanded the Āḷavi monks]: “How is that you, foolish men, will cut trees and cause them to be cut! People perceive life in trees, foolish men. This is not, foolish men, for the faith of the faithless... And thus, monks, you may recite this training rule -- In destroying plant-life: a Pācittiya.”

“People criticized and complained and spread it about, ‘How can these Sakyan-son monks cut down trees and have them cut down? They are mistreating one-facultied life.’”

Both go on to state with what exactly qualifies as plant life as well as the intricacies of why this may have been an important rule.

Thanissaro Bhikkhu wrote:The Pali term for living plant—bhutagama—literally means the home of a being. This the Sub-commentary explains by saying that devatas may take up residence in plants standing in place by means of a longing on which their consciousness fastens (at the end of their previous lives) as in a dream. This rule is justified, it says, in that the etiquette of a contemplative precludes doing harm to the abodes of living beings. As the origin story shows, though, the reason this rule was laid down in the first place was to prevent bhikkhus from offending people who held to the animist belief that regarded plants as one-facultied life having the sense of touch.
The Vibhanga defines bhutagama as vegetation arising from any of five sources:
1) from bulbs, rhizomes, or tubers (e.g., potatoes, tulips), 2) from cuttings or stakes (e.g., willows, rose bushes),
3) from joints (e.g., sugar cane, bamboo),
4) from runners (e.g., strawberries, couch grass), or
5) from seeds (e.g., corn, beans).

There's more to be said in both Thanissaro Bhikkhu's and Bhante Suddhaso's texts, so check 'em out.

"Just as a large banyan tree, on level ground where four roads meet, is a haven for the birds all around, even so a lay person of conviction is a haven for many people: monks, nuns, male lay followers, & female lay followers." —AN 5.38 | Blog at http://dhammareflections.wordpress.com